The present invention relates to an airbag and an airbag arrangement mounted, for example, to a steering wheel of a motor vehicle.
Airbag arrangements, which are mounted, for example, to steering wheels of motor vehicles, include an airbag that is inflated by inflow gas in the event of a collision for alleviating an impact to be applied to a vehicle occupant or a passenger. The airbag includes two circular nylon woven base cloths or panels, the outer peripheries of which are sewn together to have a shape like a flat bag. The vehicle body-side base cloth has a mounting hole, the periphery of which is fixed to a steering-wheel main body, and from which gas is introduced into the airbag 1. Normally, the airbag is received, in tiny fold, in the steering-wheel main body, and when an inflator is actuated, it is inflated toward the occupant by gas injected from the inflator so as to hold and restrain the occupant thrown forward, alleviating a collision impact to be applied him or her.
The airbag, demanded to develop flatly widely, is constructed, for example, to connect the passenger-side base cloth and the body-side base cloth by a tether belt. Moreover, as disclosed, for example, in JP-B2-2631300 and EP 0775614 A2, the airbag is constructed to connect the passenger-side base cloth and the body-side base cloth by a cloth with gas introducing holes so as to successively introduce gas injected from the inflator into inner sections. Such airbags have a restricted shape upon completion of development to carry out effective restraint of a passenger in a normal posture. Moreover, JP-A 8-192703 shows an airbag including a cloth panel for controlling gas flow to the outer periphery.
In these days, there is an increasing demand for airbags having excellent development characteristics that contribute to alleviation of the pressure to be applied to an occupant. In view of this, airbags are proposed which include a plurality of compartments arranged in layers for improvement of development characteristics, wherein gas is introduced first into the compartment disposed on the side of a vehicle body, which is evacuated from the compartment disposed on the side of an occupant or an object to be restrained. In order to obtain a flat shape at the initial stage of development, a middle base cloth for defining the body-side compartments receiving gas first is sewn to a body-side base cloth in a plurality of positions, and has a center portion fixed to a retainer by a screw or restricting means. After obtaining flat development of the body-side compartment, gas is introduced into the passenger-side compartment from a gas communicating port formed at the outer periphery of the middle base cloth, which is evacuated outside from an exhaust port formed in the passenger-side compartment.
With the airbags including the middle base cloth having the center portion fixed by the restricting means, the middle base cloth can easily be set with regard to its dimension of protrusion, while it is complicated in structure due to need of reinforcement, which complicates the manufacturing process of the airbags and their assemblage to airbag arrangements.
It is, therefore, an object of the present invention to provide an airbag and an airbag arrangement that ensure excellent development characteristics with reduced manufacturing cost.
One aspect of the present invention lies in providing an airbag, comprising:
base cloths arranged in layers and between a support and an object to be restrained;
compartments defined by said base cloths;
communicating portions arranged in the vicinity of an outer periphery of the airbag, said communicating portions ensuring communication between said compartments;
an exhaust portion arranged in one compartment on the side of said object, said exhaust portion being disposed at an inner periphery of the airbag with respect to said communicating portions, said exhaust portion communicating with the outside;
an introduction portion arranged in another compartment, said introduction portion being disposed at said inner periphery with respect to said exhaust portion, said introduction portion serving to introduce gas into the airbag; and
fixing portions arranged around said introduction portion, said fixing portions connecting said base cloths for defining said another compartment.
Another aspect of the present invention lies in providing an airbag arrangement, comprising:
a support fixed to a vehicle-side member;
an airbag mounted to said support for restraining an object, said airbag including:
base cloths arranged in layers and between said support and said object,
compartments defined by said base cloths,
communicating portions arranged in the vicinity of an outer periphery of the airbag, said communicating portions ensuring communication between said compartments,
an exhaust portion arranged in one compartment on the side of said object, said exhaust portion being disposed at an inner periphery of the airbag with respect to said communicating portions, said exhaust portion communicating with the outside,
an introduction portion arranged in another compartment, said introduction portion being disposed at said inner periphery with respect to said exhaust portion, said introduction portion serving to introduce gas into the airbag, and
fixing portions arranged around said introduction portion, said fixing portions connecting said base cloths for defining said another compartment; and
a housing receiving said airbag, said housing including a door that opens rotatively upon inflation of said airbag.
Still another aspect of the present invention lies in providing, in a motor vehicle:
a member;
a support fixed to said member;
an airbag mounted to said support for restraining an object, said airbag including:
base cloths arranged in layers and between said support and said object,
compartments defined by said base cloths,
communicating portions arranged in the vicinity of an outer periphery of the airbag, said communicating portions ensuring communication between said compartments,
an exhaust portion arranged in one compartment on the side of said object, said exhaust portion being disposed at an inner periphery of the airbag with respect to said communicating portions, said exhaust portion communicating with the outside,
an introduction portion arranged in another compartment, said introduction portion being disposed at said inner periphery with respect to said exhaust portion, said introduction portion serving to introduce gas into the airbag, and
fixing portions arranged around said introduction portion, said fixing portions connecting said base cloths for defining said another compartment; and
a housing receiving said airbag, said housing including a door that opens rotatively upon inflation of said airbag.